1. Field of the Invention
The present invention relates to a method of and an apparatus for controlling a substrate processing apparatus, which successively conveys substrates, such as semiconductor wafers and liquid-crystal display substrates, to a plurality of processing units via a preset transport path and processes the conveyed substrates.
2. Description of the Related Art
In a conventional substrate processing apparatus, substrates are successively conveyed to the respective processing units by a conveyance robot and subsequently processed in the respective processing units according to a preset order of transporting the substrates to the processing units (preset transport path) and a predetermined processing recipe for defining the processing conditions in the respective processing units. In the course of processing the substrates, there are some situations in which an alarm is given to inform the user of the occurrence of some abnormality in one of the plurality of processing units. When the alarm is raised, the conventional system immediately stops the conveyance of the substrates and suspends the processing thereof.
According to some processing programs, the longest time period required for the processing of substrates in a particular processing unit (hereinafter referred to as the 'longest-processing time unit') is longer than the time period required for one cycle of conveyance by the conveyance robot. The time required for one cycle of conveyance is the total time period required for transferring the substrates in the processing units to subsequent, corresponding processing units. In such a case, a delay occurs before the conveyance robot transfers the next substrate to the longest-processing time unit (hereinafter referred to as the conveyance waiting time). The processing in the longest-processing time unit thus becomes the rate-determining stage in the system and restricts the operation rate of the entire substrate processing apparatus. When a conveyance waiting time arises, the conventional system stops the conveyance of the substrates, and suspends the processing thereof.
When the processing of the substrates is interrupted, the substrates currently being processed may be adversely may be affected. For example, when the process of heating treating substrates is interrupted, the heat treatment time would be longer than planned, thereby causing over-baking (i.e., excessive heat treatment).